The ballad of Big Sue

She was a friend to Leigh Bowery, a muse to Lucian Freud, yet through it all, Sue Tilley held down her job at Charing Cross jobcentre. In the week she sold one of Freud's sketches of herself for £26,000, she talks to Tim Dowling about Taboo, tattoos, and seeing herself on Broadway

Sue Tilley has a plaque on her office wall commemorating her 25 years working for the jobcentre, and not much else. The room is functional to the point of bareness, apart from the sandalled foot sticking out from under the desk, with its bright pink toenails and casual spray of tattooed stars. She has a matching set of stars on her right shoulder and a lily on her left arm. "I've only got the three," she says, her voice a melodious version of Janet Street-Porter's, if you can imagine such a thing. "I still think they're a bit common."

Neither did the tattoos please the painter Lucian Freud, for whom Sue Tilley posed over four years in the early 1990s. "It wasn't the fact that he didn't like the tattoos," she says. "It was the fact that the colour disturbed him. Because he adores flesh so much, and to have sort of green flesh and pink flesh isn't really normal." Freud covered the tattoos with flesh-coloured paint before he set to work.

On Tuesday a Freud etching owned by Tilley (the only one to feature one of her tattoos) sold at auction for £26,180, nearly double the estimate. She isn't at all hard up, you understand, though she may have inadvertently given that impression when she told a reporter about the time the bailiffs came round chasing £700 and fancied her electric kettle over her Freud etching. "It was years ago," she says. "It was only cos I hadn't paid my poll tax, out of principle. I had the money to pay them."

Now 48, Tilley has acquired a kind of cultish tripartite fame - as Freud's fleshy muse for an important series of works; as "Big Sue", the close friend, confidante and biographer of the performance artist Leigh Bowery (who also posed for Freud), and as someone who through it all hung on to her day job, rising to her current position as manager of the Charing Cross jobcentre in Denmark Street. She once said that Freud picked her as his model because she was so ordinary, but she is now prepared to refute that. "I think he probably picked me because he got value for money," she says. "He got a lot of flesh."

She has also said that she is essentially an unambitious person, who has always lived in the same three-room flat, and that she likes the calming mundanity of the civil service. She admits this is more or less accurate. "But I try to make it as glamorous as I can," she says.

I glance at the four bare walls. "I love what you've done in here," I say.

"Well, my room's not very glamorous. What I like is having openings and that." She recently organised an exhibition on the history of the jobcentre, at the jobcentre, which was attended by Rupert Everett. For the most part she is content to wait to be asked to do things. "I never go out of my way to make things happen, cos I feel they'd be doomed," she says. "So I let things happen to me, and nice, interesting things happen to me all the time."

Tilley was first introduced to Freud by Leigh Bowery in 1990, but didn't pose for him until a year later. "Then I went away to India and got so brown he was repulsed by me, and I had to wait about a year for the suntan to fade off. And then I did another three pictures."

She describes posing for Freud as "very entertaining. He's fantastic. The most amusing person I've ever met. It was just very interesting to get lots of chat, lots of stories, to get taken to nice restaurants and get to meet all the other people he painted. That was my favourite thing, really."

Modelling for the artist was also extremely time-consuming, however, with an average canvas taking nine months to complete. "I worked there every Saturday and Sunday, and every time I had off work he used to make me go there."

Tilley first met Leigh Bowery in 1982, and worked as a cashier in his legendary nightclub, Taboo. "That was a marvellous job because Leigh was so generous with money. If he took a lot of money, he just paid you loads. He was a fool, really."

The Taboo experience, she says, was never really about the music, which was more or less the same week in, week out anyway. "One time [the DJ] was so drunk he played the turntable mat. And people still danced." The club was, for Tilley, "just a chance to see my friends and get drunk and fall over and have a laugh". And she still made it in to the jobcentre every day. "I'm very reliable. I never had any sick days or anything," she says. "But in those days clubs didn't stay open late, so I was home by three."

Taboo has in the past two years been immortalised in the West End musical of the same name. Boy George's tribute to Leigh Bowery even features a character called Big Sue. Tilley admits she was thrilled at being portrayed on stage. "But the most exciting thing ever," she says, "was when it opened on Broadway and they flew me over there. I was so excited you can't imagine. I was beside myself. And my part was much bigger over there. They even had a little jobcentre on the stage." The US version was also, she says, wildly inaccurate in parts, with "nightclub permits" being issued through the jobcentre and Big Sue using her authority to get Bowery work.

Tilley's biography of Bowery, The Life and Times of an Icon, has been bought by Hart Sharp Entertainment, the producers of Boys Don't Cry, but the right script has yet to materialise. "The film of the book? Goodness knows," says Tilley, "but to be honest, the people who bought the film are now my very good friends. I'm going on holiday with Jeff Sharp on Saturday." She hopes the film will one day be made, she says, "because I think Leigh deserves a bigger audience".

As for herself, she retains her fierce lack of ambition, demurring when friends pester her to write her own life story: "I think I could only do it if a publisher asked me to. I couldn't just do it of my own accord, cos I'm too lazy."

While she doesn't really like to plan things, she does have a future for herself mapped out, although she has a hard time keeping a straight face while explaining it. "I'll probably just work here 'til I'm 60," she says, a tight smile curling up her lips. "Then I'll retire, and then my plan is to go and live the winter in India, cos I like it there, and your pension would go ever such a long way. And then I'd very much like to have a tearoom in the Isle of Wight." She's laughing now, trying to force the words out. "I don't know why. I'm very fond of the Isle of Wight."